Conventionally, a solid-state image pickup device, which includes a large number of image pickup regions, and an optical element having microlenses etc., on a semiconductor wafer, is hermetically molded after electrical interconnects have been formed, and is used as a photosensor for digital video equipment, such as a digital still camera, a camera for a mobile telephone, a digital camcorder, etc.
Various methods have been proposed as a method for manufacturing such a solid-state image pickup device (see, for example, Patent Literature 1 and Patent Literature 2).
Patent Literature 1 discloses a method for manufacturing a microlens in which a gap between each microlens made of inorganic film is reduced, and a distance from a photodiode to the microlens is reduced, thereby improving sensitivity characteristics of a solid-state image pickup element.
Patent Literature 2 discloses a method for manufacturing a microlens including two layers.